Welcome Guest - Sign Up today
Welcome Guest - Sign Up today



Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
See more
See less

Drilling out the exhaust.

  • Filter
  • Time
  • Show
Clear All
new posts

  • Drilling out the exhaust.

    I have a Mercury 115. How do I drill out the exhaust so it sounds louder while in the water and give the motor more power. I saw a guy on the river one day who said he had done this before. Just wondering if it is possible and how to do it.

  • #2
    Re: Drilling out the exhaust.

    Ayuh,... It Ain't that Simple, 'n this Ain't a Prop question....

    I'll ge this moved to the Mercury Outboard forum...


    • #3
      Re: Drilling out the exhaust.

      Sounds like he was a pulling on your leg!!!The only way to get more power from drilling out anything is reboring the cylinders.Then u will only get maybe 5 hp more.
      Usually getting more power means a bigger motor.J

      Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
      ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

      In Scenic , Beautiful San Sebastian by the sea Florida

      88 Bayliner 21CC 2001 Mercury 225 HP EFI


      • #4
        Re: Drilling out the exhaust.

        The only way drilling holes can provide more "power" are this one...

        This mod can give you a bit more power out of the hole IF you got the right boat/engine combo..

        Drilling the exhaust other ways will in most cases just make more noise and weaken your driveshaft housing ( leg ).

        Arne Kjetil
        My engines :
        Mercury TII, next project
        Johnson V4m-10s 90 hp 1964,from the prosess.
        Mercury L6 ,Rebuilding a Tower


        • #5
          Re: Drilling out the exhaust.

          1st problem, noise ordinances, get loud, get noticed, get ticketed.

          2nd problem, IF, (notice that's big), IF, you did manage to get more air to flow, that would change the fuel/air mixture and melt pistons. It ain't so easy to jet an outboard, but it can be done, just be ready to rebuilt it if/when you smoke it til you get it right.

          The extreme low pressure area created behind the prop hub by forward movement in the water works VERY well in scavaging/pulling the exhaust out of the motor.

          It is VERY difficult to improve on Merc engineering, they have been doing this for quite a while.
          Last edited by CharlieB; February 20th, 2011, 07:17 AM. Reason: spelling


          • #6
            Sign up today
            Re: Drilling out the exhaust.

            More noise does not make more power. It just makes for more annoyed folks on the water.